COMPARISONS OF HEMI-INATTENTION PRODUCED BY UNILATERAL LESIONS OF THEPOSTERIOR PARIETAL CORTEX OR MEDIAL AGRANULAR PREFRONTAL CORTEX IN RATS - NEGLECT, EXTINCTION, AND THE ROLE OF STIMULUS DISTANCE

Neglect in human and non-human primates has been demonstrated followin g unilateral lesions of both posterior parietal and prefrontal areas. While it has now been well established that a unilateral lesion of the rodent analog of dorsolateral prefrontal cortex, medial agranular cor tex (AGm), results in neglect, the effects of unilateral damage restri cted to rodent posterior parietal cortex (PPC) have not been examined in detail. The current study assessed rats with unilateral lesions of PPC or AGm on their ability to orient to unilateral and bilateral stim ulation. Since it has been proposed in both the primate and rodent lit eratures that frontal areas may be responsible for the perception of n ear space while parietal areas may be responsible for far space, stimu li were presented at two different distances. Lesions of PPC and AGm r esulted in severe neglect relative to control operates, with both PPC and AGm operates manifesting severe hemi-inattention and allesthesia r elative to control operates. After behavioral recovery from neglect th ere was no evidence of extinction to bilateral simultaneous stimulatio n. While neglect to visual stimuli predominated in unilateral PPC oper ates, unilateral AGm operates had severe neglect in all modalities. In addition, while both left and right PPC operates showed contralesiona l neglect, AGm operates demonstrated the lateralized differences in ne glect reported in previous studies. All groups demonstrated an approxi mately equivalent level of neglect to stimuli presented at the two dif ferent distances, and thus failed to support the suggestion of a perip ersonal-extrapersonal dichotomy between frontal and parietal areas in rodents.